Fighting continues in eastern Ukraine despite a ceasefire agreement reached earlier this month by European negotiators.

While Russian-backed separatists began to pull back some heavy weapons from the front lines on Tuesday as part of the deal, Ukraine says the rebels are still initiating attacks. Ukrainian forces retreated from the strategic rail hub Debaltseve last week under an onslaught from the separatists—who were bolstered by Russian troops and advanced weaponry, Western officials said—and residents now fear that the rebels could launch further attacks on the eastern cities of Mariupol and Kharkiv.

President Obama’s drive to normalize ties with communist Cuba is raising new concerns among security officials and experts that the administration will give up the strategic naval base at Guantanamo Bay in deal with Havana.

Sen. Marco Rubio (R., Fla.) called on the White House to cancel upcoming diplomatic talks with Cuba until the Castro regime follows through on its agreement to release 53 political prisoners in a letter to President Obama on Tuesday.

On Sunday, President Obama defended his latest effort to work with Cuba as a calculated diplomatic effort and responded to critics who say the policy is yet another example of the president being too quick to appease bad actors.